Method for constructing dentures

ABSTRACT

In the construction of dentures, a method for calibrating an articulator, comprising the steps of forming a set of intra oral gothic arch traces, the traces defining a three dimensional envelope of motion, and utilizing the intra oral traces to form a substantially identical second set of gothic arch traces on the articulator, whereby relative movement of the articulator may be confined to the envelope of motion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to the field of dentistry, and inparticular, to a novel method and novel apparatus for constructingdentures.

2. Prior Art

In the construction of dentures, one of the most significant problems isto orient the upper and lower casts, in which the artificial teeth areset, relative to one another, in such a manner that the movements of themandible and its neuro-muscular influences will be modeled in a true andreproducible form. Such movements, or registrations, must not only bereproducible, but definite and durable as well. Further, once suchregistrations are made, it must be possible to transfer theregistrations to an instrument such as an articulator, withoutintroducing any error, in order to actually construct a dentition thatwill be in agreement with the original registrations of jaw movement.

The human jaw is capable of the widest variety of movements. Modellingsuch movements is complicated by the fact that the lower jaw is notmerely connected by a hinge, and is capable of translational movement aswell. Accordingly, when seeking to model or reproduce such movement, onemust be concerned with rotary or hinge-like motion, which depends uponthe centers of rotation of the condoyles with respect to the glenoidfossa, as well as translational motion, which results from motion of thecondoyle along the articular eminence. Other movements result from thecombination of rotary and translational motion, as well as from bodily(mandibular) motion, or Bennett movement. To further complicate matters,all of the foregoing are controlled to some extent by biological factorsin the formation of ligaments, meniscus and musculature, emotionalfactors and habit patterns, as well as the shape of the bony structures,including condoyle, articular eminence, articular fossa and incisalguidance, if present. Incisal guidance is not present as such in totallyedentulous mouths.

All of the foregoing factors contribute to the definition of a threedimensional envelope of motion, which defines or describes all of thenatural movements of the jaw for any particular person.

Intra oral tracing apparatus are known which utilize moldable materialand scribing pins for forming what are called gothic arch traces. A setof at least three such gothic arch traces, made in accordance withrelative movements of the human jaw, accurately define the threedimensional envelope of motion described above. Although some suchapparatus are known, their accuracy has been to limited avail, becauseno articulators are known in the art which can utilize such gothic archtraces in a manner which precisely models or reproduces the threedimensional envelope of motion unique to each individual.

This deficiency in the prior art is due to an unjustified belief thatthe solution lies in the development of a so-called universalarticulator, which is capable of reproducing each and every movement ofeach and every jaw. The prior art is replete with such articulators,each of which utilizes some form of hinged or pivotal connection inorder to simulate movement between upper and lower dentures, andtherefore upper and lower jaws.

In a distinct departure from this prior art, this invention teaches theelimination of the so called universal articulator, and instead, teachesa means by which an articulator may be programmed or calibrated to suiteach individual patient, the method and apparatus being not only asaccurate as humanly possible, but being quick and inexpensive as well.In the construction of dentures, a method for calibrating anarticulator, according to this invention, comprises the steps of forminga set of intra oral gothic arch traces, the traces defining a threedimensional envelope of motion, and utilizing the intra oral traces toform a substantially identical set of gothic arch traces on thearticulator, whereby relative movement of the articulator may beconfined to the envelope of motion. An articulator according to thisinvention for constructing dentures, for use with a gothic arch tracingapparatus, comprises first and second members, having means for holdingthe members in spaced relationship, without being connected, and havingmeans for mounting dental casts between the members, said casts havingtracing apparatus disposed therein, in operable relationship, and meansfor forming a set of gothic arch traces, for controlling relativemovement of the members, in accordance with movement of the tracingapparatus.

Only one unhinged articulator is known in the art, however, it too seeksto be a universal articulator, by reason of its reliance on removableanalog blocks to define movement of the articulator. Further, thisarticulator has upper and lower frames, each of which has a definedhorizontal axis of rotation and a centric reference device for centeringthe upper frame laterally with reference to the lower frame. Suchpredefined axes and references introduce errors into the modellingprocess before it has even begun. By way of contrast, the method andapparatus taught herein make no such predefinitions, and are thereforesignificantly more accurate.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an improved method forconstructing dentures.

It is another object of this invention to provide improved apparatus forconstructing dentures, including intra oral tracing apparatus andarticulator.

It is a further object of this invention to provide method and apparatusfor constructing dentures wherein movements of the jaw may be recordedand substantially identically reproduced.

It is yet another object of this invention to provide method andapparatus for constructing dentures wherein the articulator can becalibrated to precisely model the envelope of motion which uniquelydescribes the movement of each individual jaw, rather than utilizing thenearest approximation of a universal articulator.

It is yet another object of this invention to provide method andapparatus for constructing dentures wherein intra oral gothic archtraces may be reproduced in an unhinged articulator.

These and other objects of this invention are accomplished by the methodfor calibrating an articulator, comprising the steps of forming a set ofintra oral gothic arch traces, the traces defining a three dimensionalenvelope of motion, and utilizing the intra oral traces to form anidentical second set of gothic arch traces on the articulator, wherebyrelative movement of the articulator may be confined to the envelope ofmotion.

In connection with this method, there is provided an intra oral tracingapparatus, comprising a tracing member and a scribing member, each ofthe members having means for removably mounting the member in apatient's mouth, and one of the members having universal adjustmentmeans, the adjustment means being provided with locking means accessiblethrough the patient's mouth.

In connection with this method an articulator is also provided, for usewith gothic arch tracing apparatus, comprising first and second members,having means for holding the members in spaced relationship, withoutbeing connected, and having means for mounting dental casts between themembers, said casts having said tracing apparatus disposed therein, inoperable relationship, and means for forming a set of gothic archtraces, for controlling relative movement of the members in accordancewith movement of the tracing apparatus.

Taken together, the method and apparatus provide a novel and highlyaccurate system for constructing dentures.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating this invention, there are shown in thedrawings forms which are presently preferred, it being understood,however, that this invention is not limited to the precise arrangementsand instrumentality shown.

FIG. 1 is an exploded perspective view of an intra oral tracingapparatus in accordance with this invention;

FIG. 2 is a perspective view, in diagramatic form, of the intra-oraltracing apparatus of FIG. 1 as mounted to upper and lower casts;

FIG. 3 is a top view of a typical set of gothic arch traces;

FIG. 4 is a perspective view of an articulator in accordance with thisinvention;

FIG. 5 is a front view of the articulator of FIG. 4, having the tracingapparatus of FIGS. 1 and 2 mounted thereto, in order to reproduce thegothic arch traces of FIG. 3 on the articulator, the front leg of thearticulator having been omitted for clarity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An intra oral gothic arch tracing apparatus according to this inventionis shown in FIG. 1. The tracing apparatus 10 comprises a tracing member12 and a tracing table 14.

The tracing member 12 comprises universal adjustment means, includingfront and rear block members 16 and 18, split ball 20 and threadedmember 22. Threaded member 22 is insertable in threaded bore 24, inorder to provide for verticle adjustment of the tracing member 12 withrespect to the tracing table 14. Split ball 20 is rotatably andpivotally mounted within corresponding hemispherical grooves 26 in frontand rear blocks 16 and 18. This provides for angular adjustment of thetracing member 12 with respect to the tracing table 14. Split ball 20and threaded member 22 may be locked into position by lock screws 28,which fit through bores 30, each of which is provided with a counterbore 32 within which the heads of screws 28 will be disposed. Thelocking screws 28 are attached to rear block 18 by means of threadedbores 34, the heads of screws 34 exerting pressure against the walls ofcounter bores 32. Locking screws 28 may be provided with hex heads, inorder to facilitate locking the member into position after it has beeninserted into a patient's mouth. The upper surfaces 36 and 38 of frontand rear blocks 16 and 18 respectively are provided with scores ordepressions, in order to facilitate mounting the entire tracing member12 as will be hereinafter described in more detail. A substantiallyequilateral triangular member 40 is fixedly secured to the bottom ofthreaded member 22, at right angles thereto. Members 22 and 40 may beadhesively bonded, soldered, spot welded, screwed or bolted together.Threaded member 22 may also be the shank portion of a bolt which ismounted through a hole in triangular member 40 from below, and securedthereto by any of the methods just described. Many means are available.Mounted near each corner of triangular member 40 is a stylus member 42,having a rounded point. Each stylus 42 may be attached in a mannersimilar to that described in connection with mounting triangular member40 to threaded member 22. As a further alternative, each stylus 42 maybe provided with a threaded base section, which can be screwed directlyinto a threaded bore in triangular member 40. At least three stylii 42are necessary, but more may be used if desired.

Tracing table 14 is a substantially flat member, having a semicircularor rounded triangular configuration, which conforms generally to thecurvature of the lower jaw. Tracing table 14 is provided with aplurality of notches 44 which aid in securing the tracing table as willbe hereinafter described. Tracing table 14 may also be provided with araised lip 46 along its straight edge.

FIG. 2 illustrates the tracing apparatus of FIG. 1 as it is attached ina patient's mouth. Although upper and lower dental forms or models 48and 50, often termed casts, are illustrated, the mounting of the tracingapparatus is identical to that within a patient's mouth. During thecourse of constructing dentures, it is of course necessary in thismethod, as well as all other methods, to make upper and lowerimpressions of the patient's jaw. This is usually done with specialmodelling compounds or the like 52, which are pressed in and around thegums and existing teeth, for both the upper and lower jaw. The tracingmember 12 and tracing table 14 are pressed into the modelling material52 in the upper and lower jaws respectively, such that the tracing table14 is substantially parallel to the lower jaw line, and the front andrear block assembly is substantially parallel to the upper jaw line.

Once the tracing member and tracing table have been embedded in themodeling material in the upper and lower jaws, the apparatus may beadjusted as follows. The patient is asked to hold his or her mouth openin a "natural" and comfortable position. Triangular member 40 may thenbe rotated, in order to increase or decrease the vertical distancebetween the triangular member 40 and the tracing table 14. After thevertical distance has been adjusted, to the natural position of the jawfor each individual patient, the triangular member 40, may or may not beparallel to tracing table 14. It is pivoted until it is substantiallyparallel, and then locking screws 28 are tightened, which may beconveniently accomplished by use of a hex, allen, ball or other suitablewrench inserted through the patient's opened mouth.

After the tracing apparatus has been adjusted, the patient is asked toopen the mouth wide enough to enable the dentist or technician to coverthe tracing table with a quick curing acrylic adhesive 54, or othermoldable material. This can also be done outside the mouth beforeinsertion of the tracing table into the mouth. The patient is then askedto open and close his or her mouth and to move the lower jaw in and out,back and forth, side to side, up and down and in any and all directionswhich feel natural, and which are not unduly exaggerated. During thismotion, each stylus 42 will be displacing the acrylic material 54,forming a hole or groove therein. The motion of the jaws will take intoaccount right and left lateral extremes, protrusive and retrusivemovements and lateral protrusive right and left movements. Thesemovements represent a three dimensional envelope of motion which isnatural for any particular patient, and the grooves or traces formed inthe moldable material are known as gothic arch traces. A set 58 of suchtraces is shown in FIG. 3. As shown, at least three such traces arenecessary, although more may be made if desired.

After the moldable material has hardened or set, the upper and lowercarrying trays, with the tracing apparatus still embedded, may beremoved from the patient's mouth and inserted into the forms or casts 48and 50, as shown in FIG. 2. The upper and lower casts may be providedwith mounting means, such as substantially triangular plates 56, whichare utilized to attach the casts to an articulator. These plates areembedded in modelling material 52 on the back of each cast. It may beemphasized that there has been obtained a set of gothic arch traceswhich define an envelope of motion unique to each individual patient.

An articulator in accordance with this invention is shown in FIGS. 4 and5. The articulator 70 comprises an upper member 72 and a lower member74. Upper member 72 has a central portion 76, from which project threearms 78, having substantially equal angles of 120° between them.Projecting downwardly, with respect to the orientation of FIG. 4, fromeach arm 78 is a combination leg and tracing stylus member 80, having arounded point 82. Members 80 may, for example, be attached to arms 78 byany of the methods described in connection with fixing threaded member22 to triangular member 40. Central portion 76 is also provided withmounting means 84, comprising three unthreaded bores for use in mountingthe upper cast.

Lower member 74 is substantially T-shaped, with the ends of each leg 86corresponding in position to stylus members 80. At the end of each arm86, directly below each stylus member 80 is a hollow or depression 88,into which a further charge of the acrylic molding material or the like54 may be placed. In the central portion of member 74 is disposedanother set of mounting means 90 similar to mounting means 84. Themounting means 84 and 90 correspond in position to mating mounting means92 in each mounting plate 56. Mounting means 92 comprises one threadedbore and two index pins, the pins preferably having somewhat taperedtips. The upper and lower casts may therefore be easily attached to theupper and lower members of the articulator by one machine screw each orthe like, inserted through one of the bores of mounting means 84,alignment being assured by the prior insertion of the indexing pins.

After the intra oral tracing has been accomplished, the molding material52, with tracing apparatus attached thereto, is removed from the mouthand mounted onto the upper and lower casts. The upper and lower castsare then attached to the members of the articulator, by means of themounting plates 56 embedded therein. Ideally, when the casts are somounted, and the upper member of the articulator rests on the tracingassembly, the tracing table and tracing stylii of the articulator willbe approximately 1 millimeter apart. This distance can be adjusted inthe course of affixing the casts to the articulator, by methods known inthe art.

After the casts have been mounted to the articulator, the upper memberand upper cast are removed in order that more of the acrylic moldingmaterial may be placed into each of the depressions 88. The point 82 ofeach stylus is lubricated with silicone, and the upper member of thearticulator is carefully placed back into position, with the stylii ofthe tracing apparatus resting within the original gothic arch traces. Atthis point, the tracing stylii are in intimate dynamic contact with thegothic arch traces. By holding both members of the articulator, with theaid of finger and thumb holds 92, and passing the original tracingthrough all of its excursions, the original gothic arch traces can besubstantially identically reproduced on the articulator. The original,dynamic, patient derived articulation information is thereforesubstantially identically reproduced on the instrument which will beused to build a specific dentition for a particular patient. After thearticulator has been moved through all of its excursions, the uppermember thereof is removed in order that the acrylic molding material canharden or set. Once hardened, the tracing apparatus can be removed fromthe molds or casts, and artificial teeth can be inserted in theconventional fashion. It may be appreciated that even though thedentition is constructed in the conventional manner, when placement ofteeth is tested by further excursions of the articulator, suchexcursions still represent the unique three dimensional envelope ofmotion generated for that particular patient. Placement of the teethneed not be tested against the predisposed "universal" movements ofprior art articulators. As a further advantage, the manner in which thearticulator may be prevented from moving within the defined envelope ofmotion determined by the gothic arch traces offers insightfulinformation as to the orientation in which any particular teeth havebeen incorrectly placed, as well as what steps should be taken tocorrect the misplacement. Accordingly, even the conventional placementof teeth within the dentition can proceed at a quicker pace.

Due to the fact that the articulator may be substantially contructedfrom inexpensive materials, such as metals, plastics, or even wood, thelower members, with gothic arch traces molded thereon, may be easilystored in case any future or further work must be done on the patient'sdentition.

Taken together, the method and apparatus taught herein provide a noveland highly accurate system for obtaining a patient's "envelope ofmotion" during tooth contact and swallowing acts, and for transferringthe "envelope of motion" to an articulator where it forms the basis foraccurate and intelligent construction of full upper and lower dentures.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, andaccordingly, reference should be made to the appended claims rather thanto the foregoing specification as determining the scope of thisinvention.

I claim:
 1. In the construction of dentures, a method for calibrating anarticulator, said method comprising the steps of:(a) rigidly andintra-orally mounting a tracing table member to one of a patient's upperand lower jaws; (b) rigidly and intra-orally mounting a scribing memberto the other of said patient's jaws; (c) adjusting and locking theangular relationship and distance between bearing surfaces of saidtracing table and said scribing member to bring said bearing surfacesinto contact when said jaws are held slightly apart; (d) forming a firstset of three gothic arch traces, the traces defining a three-dimensionalenvelope of motion; and, (e) utilizing the first set of traces to form asubstantially identical second set of gothic arch traces on thearticulator, whereby relative movement of the articulator may beconfined to the envelope of motion after the first set of gothic archtraces has been removed.
 2. The method of claim 1, wherein the first setof gothic arch traces is patient generated by natural jaw movement whilethe angular relationship and distance between said bearing surfaces arelocked in the adjusted position.
 3. The method of claim 1, wherein anintra oral tracing apparatus is first inserted into a patient's mouth,and charged with a molding material, the first set of gothic arch tracesbeing formed in the material in accordance with movement of thepatient's jaw.
 4. The method of claim 1, wherein the tracing apparatusis charged with the molding material prior to insertion into thepatient's mouth.
 5. The method of claim 1, wherein said adjustment ismade by positioning and locking a universally-adjustable mechanismhaving a base member rigidly mounted to one of said jaws and a bearingsurface unit universally-adjustable thereto.
 6. The method of claim 5,wherein said universally-adjustable mechanism is a threaded, slit balljoint and said base member comprises at least one locking screw.
 7. Amethod for constructing dentures, or the like, comprising the stepsof:(a) forming a first set of three gothic arch traces for movement of apatient's jaw, the gothic arch traces defining a three-dimensionalenvelope of relative jaw motion; (b) utilizing the first set of tracesto form a substantially identical second set of traces on an articulatorhaving an upper denture holding member and a lower denture holdingmember to which members said dentures may be affixed, said upper holdingmember and lower holding member being placeable one upon the other butremovable one from the other, whereby the interface of said dentures maybe limited to said envelope of motion after removal of said first set oftraces, but said dentures may be freely separated for furtherprocedures; and, (c) placing teeth in the dentures in accordance withthe defined movement of the articulator.
 8. The method of claim 7,wherein the first set of gothic arch traces is formed intra orally. 9.The method of claim 7, wherein an intra oral tracing apparatus is firstinserted into a patient's mouth, and charged with a molding material,the first set of gothic arch traces being formed in the material inaccordance with movement of the patient's jaw.
 10. The method of claim9, wherein the tracing apparatus is charged with the molding materialprior to insertion into the patient's mouth.
 11. The method of claim 7,further comprising the step of testing placement of the teeth by movingthe articulator through all excursions within the envelope of motiondefined by the gothic arch traces.
 12. The methods of claims 1 or 7,wherein the articulator comprises at least two unjoined members.